JP2014197456A - Method of positive electrode grid body for lead-acid storage battery and lead-acid storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing the positive electrode grid body for lead-acid storage battery capable of preventing short circuit of the positive electrode grid body for lead-acid storage battery due to elongation deformation caused by corrosion thereof, while suppressing reduction in mechanical strength and influence on the electrical characteristics, and to provide a lead-acid storage battery.SOLUTION: A method of manufacturing the positive electrode grid body 1 for a lead-acid storage battery in which a grid body having a frame bone 2, and a vertical bone 3 and a lateral bone 4 arranged like a grid in the frame bone are formed from a plate of lead or a lead alloy produced by any one of gravity casting, pressure casting, continuous casting or rolling, includes a step for subjecting a predetermined point of the frame bone 2 to high deformation thus forming a low corrosion resistance point.

Description

  The present invention relates to a method for manufacturing a positive electrode grid for a lead storage battery used for a positive electrode plate of a lead storage battery and a lead storage battery.

Conventionally, in a lead storage battery, an elongation of a positive electrode plate called gloss is generated. As the gloss progresses, the positive electrode lattice body expands, the upper end of the positive electrode lattice body and the negative electrode strap approach each other, and finally they come into contact with each other, resulting in an internal short circuit. It is extremely difficult to prevent the gloss, and various studies have been made on the material and structure of the grid of the positive electrode plate in order to suppress the gloss.
For example, in order to prevent a short circuit due to the gross of the positive electrode grid for lead-acid batteries, the mechanical strength of the lead-acid battery positive grid for the lead-acid battery is lessened by providing notches etc. in the frame, thereby breaking. A technique for providing a weak point to be induced in advance is known (see, for example, Patent Document 1).

Special table 2008-542997 gazette

  However, in a lead storage battery that employs a frame bone provided with a notch or the like, the lattice cross-sectional area is reduced, which affects the potential distribution of the lead storage battery and causes a reduction in performance of electrical characteristics. In addition, because the weak points that reduce the mechanical strength were formed in advance, in the manufacturing process of the positive electrode grid for lead-acid batteries, the electrode plate group was inserted into the process for filling the positive-electrode grid for lead-acid batteries and the battery case In the process, the weak points may be broken and the yield may be deteriorated.

  The present invention has been made in order to solve the above-described problems, and can prevent a short circuit caused by the gloss of the positive electrode grid for a lead-acid battery while suppressing a decrease in mechanical strength and an influence on electrical characteristics. It aims at providing the manufacturing method of the positive electrode grid for storage batteries, and a lead storage battery.

  In order to achieve the above object, the present invention is a frame made of lead or a lead alloy produced by any one of gravity casting, pressure casting, continuous casting, and rolling, and arranged in a lattice pattern in the frame bone. A method of manufacturing a positive electrode grid for a lead-acid battery that forms a grid having a vertical bone and a horizontal bone includes a step of subjecting the frame bone to strong processing to form a low corrosion resistance point.

  Further, the present invention provides the above-described method for manufacturing a lead-acid battery positive electrode grid, wherein the lead-acid battery positive electrode grid includes an ear on one side of the rectangular frame-shaped frame, and at least one side on which the ear is provided. The low corrosion resistance point is provided around one end portion.

  Moreover, the present invention is characterized in that, in the above-described method for producing a positive electrode grid for a lead storage battery, the strong processing is processing for changing the microstructure of the cross section of the frame bone to reduce corrosion resistance.

  Moreover, this invention was equipped with the positive electrode grid for lead acid batteries manufactured by the manufacturing method of the positive electrode grid for lead acid batteries in any one of the above in the positive electrode.

  According to the method for manufacturing a positive electrode grid for a lead-acid battery of the present invention, low corrosion resistance is obtained by strong processing without changing the lattice cross-sectional area that affects the mechanical strength and electrical characteristics of the positive-electrode grid for a lead-acid battery. Since the point is formed, the formation of the low corrosion resistance point can suppress the decrease in the mechanical strength of the positive electrode body for the lead-acid battery and the influence on the electrical characteristics. In a lead storage battery that employs the positive electrode grid for the lead storage battery, the low corrosion resistance point breaks before the elongation deformation due to corrosion becomes large, so that the occurrence of a short circuit can be prevented.

It is a front view of the positive electrode grid body for lead acid batteries manufactured by the manufacturing method of the positive electrode grid object for lead acid batteries which concerns on one Embodiment of this invention. It is a flowchart figure of the manufacturing method of the positive electrode plate of a lead acid battery. It is sectional drawing explaining the shape and formation method of a low corrosion resistance point. It is a figure which shows the result of the life test of the lead acid battery which concerns on one Embodiment of this invention, and the lead acid battery of a comparative example. It is sectional drawing explaining the other embodiment of the shape and formation method of a low corrosion resistance point. It is sectional drawing explaining the other embodiment of the shape and formation method of a low corrosion resistance point.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a front view of a positive electrode grid 1 manufactured by a method for manufacturing a positive electrode grid for a lead storage battery (hereinafter referred to as a “positive electrode grid”) according to an embodiment of the present invention.
In FIG. 1, a positive electrode grid body 1 is used as a current collector of a positive electrode plate of a lead storage battery mounted on an automobile or the like, for example.
The positive grid 1 includes a frame bone 2 constituting an outer frame, a plurality of vertical bones 3 and a plurality of horizontal bones 4 formed in a lattice shape inside the frame bone 2, and extends outward from the frame bone 2. And a collected ear 5 for current collection.
The frame bone 2 has a rectangular outer shape, and in FIG. 1, an upper frame bone 6 and a lower frame bone 7 that are spaced apart from each other in the vertical direction and extend in parallel, and a left frame that is spaced apart from each other in the left-right direction and extends in parallel. A bone 8 and a right frame bone 9 are provided.
The plurality of vertical bones 3 are arranged in the frame bone 2 so as to be separated from each other. One end of each longitudinal bone 3 is connected to the upper frame bone 6, and the other end of the longitudinal bone 3 is connected to any of the lower frame bone 7, the left frame bone 8, and the right frame bone 9. A plurality of horizontal bones 4 are provided so as to be spaced apart from each other in the vertical direction and pass between the left frame bone 8 and the right frame bone 9, and form a lattice in cooperation with the vertical bones 3.

Next, a method for manufacturing a positive electrode plate using the positive electrode grid 1 will be described.
FIG. 2 is a flowchart of a method for manufacturing a positive electrode plate of a lead storage battery.
The manufacturing method of the positive electrode plate includes a process of manufacturing the positive electrode grid body 1 (step S11 to step S13) and an active material filling / drying process (step S14).
The slab manufacturing process performed in step S11 is a process for obtaining lead or a lead alloy slab. In the slab casting process, first, a block or powdered lead (Pb) or a mixed metal obtained by mixing a block or powdered Pb and various metals is prepared.
When a lead alloy is used as the material, the alloy composition may be a Pb-antimony (Sb) -based alloy that has been widely used, or a Pb-calcium (Ca) -tin (Sn) -based alloy. Pb—Ca—Sn alloys have features such as self-discharge and a small amount of liquid reduction, and are useful from the viewpoint of maintenance-free.
The alloy composition of the lead alloy is not limited to this, and the metal mixed with Pb may be appropriately mixed with metals such as aluminum (Al) and barium (Ba) in addition to Ca and Sn.
Hereinafter, although the case where the positive electrode grid body 1 is made from a mixed metal will be described, the case where the positive electrode grid body 1 is made from Pb can be similarly described.
In the slab manufacturing process, a sheet-like cast body (slab) is obtained using a so-called twin roll casting machine.
That is, the mixed metal is heated and melted, and the molten mixed metal is poured between a pair of opposed metal rolls to solidify the slab, thereby obtaining a continuous sheet-like lead alloy slab.

In the rolling process performed in Step S12, a sheet-shaped lead alloy slab is sandwiched between a pair of upper and lower rolling rolls, and pressure is applied to obtain a rolled sheet in which the lead alloy slab is extended. In this embodiment, rolling was performed by adjusting the number of rolling rolls and the rolling reduction by a known method so that the thickness of the rolled sheet was about 1 mm. Rolling increases the mechanical strength as compared with the state of the lead alloy slab and facilitates the processing of the rolled sheet.
Next, in the press molding / low corrosion resistance point forming step performed in step S13, the rolled sheet is press punched using a press molding machine to obtain the positive electrode grid body 1 having the shape shown in FIG.
Here, in the press molding / low corrosion resistance point forming process, simultaneously with the press punching, the portion indicated by the broken circle in FIG. A low corrosion resistance point with further reduced corrosion resistance is formed, which will be described later.
In the active material filling / drying step performed in step S14, the positive electrode active material is filled in the lattice of the positive electrode grid 1, and the positive electrode active material is aged and dried to obtain a positive electrode plate. The positive electrode active material is filled in the positive electrode grid as a paste by kneading lead powder, dilute sulfuric acid, and water.

Next, the lead storage battery will be described.
Although not shown in detail, the lead storage battery has a configuration in which an electrode plate group is provided in a battery case. The electrode plate group is configured by alternately arranging positive electrode plates and negative electrode plates inserted in a bag-shaped separator. In this embodiment, the number of positive electrode plates is seven and the number of negative electrode plates is eight.
The negative electrode plate is manufactured by filling a negative electrode grid with a negative electrode active material, aging and drying. The positive electrode plate and the negative electrode plate are arranged in the battery case with their ears facing upward. The ears 5 of the positive electrode plate and the ears of the negative electrode plate are shifted from each other when viewed from the stacking direction. The plurality of negative electrode plate ears are connected to a common negative electrode strap, and the plurality of positive electrode plate ears 5 are connected to a common positive electrode strap.
A positive electrode terminal and a negative electrode terminal are provided on the surface of the lid portion of the battery case exposed to the outside, the negative electrode strap is connected to the negative electrode terminal, and the positive electrode strap is connected to the positive electrode terminal.
By injecting a sulfuric acid aqueous solution (dilute sulfuric acid) having a specific gravity of 1.240 into the battery case as an electrolytic solution, initial charging (battery cell formation) is performed, and voltage can be supplied between the positive electrode terminal and the negative electrode terminal.

By the way, in the positive electrode plate arranged in the battery case, when the corrosion of the positive electrode grid body 1 proceeds due to charging / discharging of the lead storage battery, the frame 2 is called gross due to the tensile stress of the corrosion product. Elongation deformation of the positive electrode grid 1 occurs. The frame 2 of the positive electrode grid 1 is surrounded by the bottom and side surfaces of the battery case, and is restricted from being deformed toward the bottom and side surfaces of the battery case. On the other hand, a space is formed above the positive electrode grid body 1 between the upper frame bone 6 of the positive electrode grid body 1 and the negative electrode strap, and the upward deformation of the positive electrode grid body 1 is not restricted. Therefore, when gross is generated in the frame 2 of the positive grid 1, the upper frame 6 tends to extend in the left-right direction and the upper direction, but the deformation in the left-right direction and the lower direction is restricted. , Deformation toward the upper direction where the deformation is not restricted.
The above-mentioned low corrosion resistance point means that the upper frame bone 6 of the positive electrode grid body 1 is a portion where the corrosion resistance has been lowered by strong processing in order to prevent the upper frame bone 6 from coming into contact with the negative electrode strap located above by the gloss and short-circuiting. It is defined as

As described above, since the stress is concentrated in the vicinity of the corner formed by the upper frame bone 6 and the left frame bone 8 or the upper frame bone 6 and the right frame bone 9, the vicinity of these corner portions is generated. It grows big.
Therefore, the low corrosion resistance points are determined at portions P1, P2 at both ends of the upper frame bone 6 where the ears 5 are formed, and portions P3, P4 of the left frame bone 8 and the right frame bone 9 near the both ends of the upper frame bone 6. Is formed.
At the low corrosion resistance point, the upper frame bone 6 that has generated the gloss of the positive electrode grid 1 is strongly processed so as to be broken before coming into contact with the upper negative electrode strap, thereby reducing the corrosion resistance.
Due to the occurrence of the gloss of the positive electrode lattice 1, the stress that tends to make the upper frame bone 6 face upward is released in the extending direction of the frame frame 2 at any broken portion when one of the low corrosion resistance points is broken. It is. For this reason, after the low corrosion resistance point breaks, the upper frame bone 6 is restrained from extending and deforming upward.
Note that the low corrosion resistance point is not limited to those formed in the parts P1 to P4 of the frame bone 2, and may be set as appropriate in consideration of the part where the positive electrode lattice 1 is desired to be prevented from being glossed. For example, the upper frame bone 6 is not limited to what is provided in both the site | parts P1 and P2. For example, when the negative strap is located above one end of the upper frame bone 6 and only the contact between the upper frame bone 6 and the negative strap needs to be taken into consideration, the negative strap is low at one end of the upper frame bone 6. It is only necessary to provide a corrosion resistance point.

Next, a method for forming a low corrosion resistance point will be described.
FIG. 3 is a cross-sectional view illustrating the shape and forming method of the low corrosion resistance point.
FIG. 3 is a cross section orthogonal to the width direction of the upper frame bone 6 and shows the periphery of the formation region of the low corrosion resistance point.
As described above, the low corrosion resistance point is performed when a punching operation is performed by a press molding machine in the press molding / low corrosion resistance point forming step performed in step S13.
The punching die 11 of the press molding machine includes an upper die 15 and a lower die 16 that sandwich a portion of the rolled sheet 12 that forms the frame bone 2 from both sides in the thickness direction. A convex portion 17 is provided at a position of the upper die 15 sandwiching the low corrosion resistance point of the rolled sheet 12, and a concave portion 18 is provided at a portion of the lower die 16 facing the convex portion 17.

As shown in FIG. 3, the wall surface shape of the convex portion 17 has a substantially circular arc shape and is pressed over the entire width direction of the upper frame bone 6. The wall surface shape of the recess 18 has a circular arc cross section. Thereby, the site | part strongly processed by being pinched | interposed between the convex part 17 and the recessed part 18 turns into a low corrosion resistance point curved in the U shape.
Here, strong processing refers to press processing in which a higher pressure is applied in the thickness direction than the main region excluding the portion to be subjected to strong processing in the formation region of the frame bone 2.
The convex portions and the concave portions forming the low corrosion resistance points by pressing the portions P3 and P4 of the left frame bone 8 and the right frame bone 9 have the same shape, and rolling by the upper die 15 and the lower die 16 is performed. When the sheet 12 is pressed, the parts P3 and P4 of the frame bone 2 are also strongly processed.

  By finely processing the frame bone 2, the microstructure in the cross section of the frame bone 2 changes. For this reason, fine crystal grains are formed in the strongly-processed part of the frame bone 2 to reduce the corrosion resistance, and the progress of corrosion is faster than in other parts. The pressure at the time of performing strong processing is set according to the target value of the decrease in corrosion resistance at the low corrosion resistance point. That is, the target value for the reduction in corrosion resistance is that the upper frame bone 6 remains in the negative strap even if gross occurs in consideration of the distance between the negative electrode strap when the lead-acid battery is manufactured and the upper frame bone 6 of the positive electrode grid 1. Set so that the low corrosion resistance point breaks before touching. Thereby, in the lead storage battery using the positive electrode grid body 1 for the positive electrode plate, a short circuit can be prevented. In addition, although a part of the frame bone 2 is deformed by strong processing to form a low corrosion resistance point, the width of the frame bone 2 at the part of the frame bone 2 where the low corrosion resistance point is formed does not change. . For this reason, before the lead-acid battery is repeatedly charged and discharged and the corrosion progresses, the mechanical strength is reduced at the low corrosion resistance point, and the influence on the electrical characteristics due to the formation of the low corrosion resistance point can be suppressed. .

The lead storage battery of this invention and the lead storage battery of the comparative example were produced by the method mentioned above. The lead acid battery of the comparative example is the same as the lead acid battery of the present embodiment except that the formation of the low corrosion resistance point in the press molding / low corrosion resistance point forming step is omitted in the method of manufacturing the lead acid battery of the present embodiment. It manufactured by the same manufacturing method. And the cycle life test was implemented using the lead storage battery produced, respectively.
In the cycle life test, a lead storage battery was discharged at a discharge current of 25 A for 2 minutes in a 75 ° C. environment, and then charged for 10 minutes at a charge voltage of 14.8 V (maximum charge current of 25 A). Each time the above process was repeated 480 cycles, the battery was discharged at a discharge current of 272A for 30 seconds, and the life was reached when the voltage at the 30th second dropped to 7.2V.
FIG. 4 is a diagram showing the results of a life test of a lead storage battery according to an embodiment of the present invention and a lead storage battery of a comparative example.
In FIG. 4, the horizontal axis represents the number of charge / discharge cycles of the lead storage battery, and the vertical axis represents the 30-second voltage. The test was terminated when the voltage at 30 seconds was lower than the voltage considered to be the lifetime in actual use of the lead storage battery.
As shown in FIG. 4, in the lead storage battery of this embodiment, the lifetime was significantly improved as compared with the lead storage battery of the comparative example.
After the test, the lead storage battery of this embodiment and the lead storage battery of the comparative example were disassembled, and the state of the positive electrode grid 1 was observed.
In the positive electrode grid body 1 of the lead storage battery of the comparative example, a significantly large gloss was observed, and the distance between some of the positive electrode grid bodies 1 and the negative electrode strap was close. Therefore, it is considered that the active material floating due to the softening of the positive electrode active material is electrodeposited on the ears of the negative electrode plate and grows in a dendrite shape to cause a short circuit.
On the other hand, in the lead storage battery of this embodiment, the location where the low corrosion resistance point was broken was seen. Thereby, in the lead acid battery of this embodiment, since the fall of the electrical property was suppressed rather than the lead acid battery of the comparative example by suppressing the gross of the positive electrode grid body 1 which goes upwards, it became long life I can judge.

The above-described embodiment is merely an example of one aspect of the present invention, and can be arbitrarily modified and applied without departing from the spirit of the present invention.
The low corrosion resistance point has been described as being formed into a U shape by subjecting the frame 2 to strong processing by the convex portions 17 and the concave portions 18 of the punching die 11. However, the low corrosion resistance point is not formed in a U shape, and may be as shown in FIGS. 5 and 6 described below, for example.
FIG. 5 and FIG. 6 are cross-sectional views for explaining other embodiments of the shape and forming method of the low corrosion resistance point.
For example, as shown in FIG. 5, the low corrosion resistance point may be obtained by reducing the thickness of the frame bone 2 by subjecting the frame bone 2 to strong processing.
In this case, the punching die of the press molding machine that performs strong processing is configured such that the upper die 21 and the lower die 22 are replaced with the upper die 15 and the lower die 16 in the punching die 11 described above.
The outer shape of the convex portion 23 of the upper die 21 is a rectangular convex surface, the inner surface shape of the flat portion 24 of the lower die 22 is a plane that substantially matches the convex surface of the convex portion 23, and the convex portion 23 and the flat portion 24. The thickness of the frame 2 is deformed by sandwiching the rolled sheet 12 between the two and performing strong processing.

Further, the low corrosion resistance point may be obtained by, for example, so-called offset deformation of the frame 2 by strong processing as shown in FIG.
In this case, the punching die of the press molding machine that performs strong processing is configured by replacing the upper die 15 and the lower die 16 with the upper die 25 and the lower die 26 in the aforementioned punching die 11.
The upper die 25 is provided with a step portion 27, and the lower die 26 is provided with a step portion 28. On both sides of the stepped portions 27, 28, the surfaces of the upper die 25 and the lower die 26 directed to the formation region of the frame 2 of the rolled sheet 12 are shifted in the direction in which the upper die 25 and the lower die 26 are separated from each other. Arranged. The upper die 25 and the lower die 26 sandwich the formation region of the low corrosion resistance point in the rolled sheet 12 with the step portions 27 and 28 from the thickness direction of the rolled sheet 12. Thereby, the site | part of the rolled sheet 12 pinched | interposed into the level | step-difference parts 27 and 28 carries out an offset deformation | transformation, and becomes a low corrosion resistance point.

Even if the low corrosion resistance point as shown in FIG. 5 and FIG. 6 is formed by subjecting the frame bone 2 to strong processing, the fine structure in the cross section of the frame bone 2 changes. Corrosion progresses faster than the site. For this reason, in the lead storage battery manufactured by adopting the positive electrode grid body 1 having these low corrosion resistance points as the positive electrode plate, short-circuiting of the lead storage battery is prevented and the life of the lead storage battery is extended.
Further, in the present embodiment, the press forming machine is described as performing strong processing when performing press molding. However, the step of forming the low corrosion resistance point by performing strong processing on the frame 2 is performed by rolling. You may provide separately from the process of press-molding a sheet | seat in a grid | lattice form.
In addition, although it described about rolling in this embodiment, it should just be able to form a low corrosion resistance point in a lattice object, and it is the same by giving the above-mentioned strong processing to a lattice object produced by publicly known gravity casting, pressure casting, and continuous casting. It goes without saying that it is possible to obtain the effect of.

DESCRIPTION OF SYMBOLS 1 Positive electrode grid for lead acid battery 2 Frame bone 3 Longitudinal bone 4 Horizontal bone 5 Ear

Claims (4)

A frame body made of lead or lead alloy manufactured by gravity casting, pressure casting, continuous casting, or rolling, and a lattice body having vertical and horizontal bones arranged in a lattice shape in the frame bone In the manufacturing method of the positive electrode grid for lead storage battery to be formed,
The manufacturing method of the positive electrode grid body for lead acid batteries characterized by including the process of giving a strong process to the said frame bone, and forming a low corrosion-resistant point. The lead-acid battery positive grid is provided with an ear on one side of the rectangular frame.
2. The method for producing a positive electrode grid for a lead-acid battery according to claim 1, wherein the low corrosion resistance point is provided around at least one end of one side where the ear is provided.   3. The method for producing a positive electrode grid for a lead storage battery according to claim 1, wherein the strong processing is a processing of changing a microstructure of a cross section of the frame bone to reduce corrosion resistance. 4.   A lead storage battery comprising a positive electrode grid for a lead storage battery manufactured by the manufacturing method according to claim 1 on a positive electrode.

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